1. Field of the Invention
The present invention relates to an LED module in which LEDs (light emitting diodes) are mounted, as well as an LED light source apparatus.
2. Description of the Related Art
Transmission type liquid crystal displays are provided with a backlight apparatus on the rear of the liquid crystal panel as a light source. Though conventional light sources for light source apparatuses used as a backlight are mainly CCFLs (cold cathode fluorescent lamps), LEDs have been expected to be used more and more as a light source instead of CCFLs as the technology develops. Japanese Unexamined Patent Publication 2003-207780, for example, (hereinafter referred to as Document 1) describes a backlight apparatus where LEDs are used as light emitting elements. In Document 1, as many LEDs as necessary are mounted on a substrate with uniform distribution, so that a light source apparatus that can illuminate the entire screen is provided. In addition, such surface illumination is also possible by aligning a number of LED modules, which are linear light sources where a number of LEDs are aligned in a line, on a substrate, as described in Japanese Unexamined Patent Publication 2008-53062, for example. In addition, in the case where a number of LEDs are aligned on a substrate, there are methods according to which LEDs are aligned in parallel, as in Document 1, or a predetermined number of LEDs are aligned in series, as in Japanese Examined Utility Model Publication S62 (1987)-34468.
Accordingly, in LED modules where a number of LEDs that are aligned in a line are connected in series on a substrate, an anode terminal 3 and a cathode terminal 4 for leading out the anode and cathode at the two ends of the number of LEDs 1 that are connected in series are provided on a substrate 2, as shown in FIGS. 25 and 26. A first case, where the anode terminal 3 and the cathode terminal 4 are provided at one end of the substrate 2, as shown in FIG. 25, and a second case, where the anode terminal 3 is provided at one end of the substrate 2 and the cathode terminal 4 is provided at the other opposite end of the substrate 2, as shown in FIG. 26 are possible. In the cases shown in FIGS. 25 and 26, examples of LED modules 50 and 51 where eight LEDs are connected in series are shown. Here, FIGS. 25A and 26A show the state before the LEDs are mounted, and FIGS. 25B and 26B show the state when the LEDs are mounted.
In the LED modules 50 and 51, nine connecting wires 11 to 19 for connecting eight LEDs 1 in series are formed on the insulating substrate 2, and the connecting wires 11 to 19 are provided so as to be separated each other and have terminals that are provided adjacently and sequentially. One end of the first connecting wire 11 is connected to the anode terminal 3, and the other end is provided with an electrode 20 formed for connection with the anode of one LED. One end of the second to eighth connecting wires 12 to 18 is provided with an electrode 21 for connection with the cathode of the LEDs respectively, and the other end is provided with an electrode 20 formed for connection to the anode of the LEDs respectively. One end of the ninth connecting wire 19 is connected to the cathode terminal 4, and the other end is provided with an electrode 21 formed for connection to the cathode of one LED. Electrodes 20 and 21 that are provided at the terminal of adjacent connecting wires are connected to the anodes and the cathodes of LEDs, so that eight LEDs 1 are connected in series in the forward direction between the anode terminal 3 and the cathode terminal 4, thus providing an LED module.
FIG. 27 is a configuration diagram showing external wires in the case where an LED light source apparatus where LEDs are aligned in a plane is formed by aligning LED modules 50 having an anode terminal 3 and a cathode terminal 4 at one end of a substrate, as shown in FIG. 25, in a 2×4 matrix. In the case where the LED modules 50 are formed so as to be parallel, as shown in FIG. 27, for example, a control substrate 42 for driving the LEDs in the LED modules 50 so that the light emission thereof can be controlled is provided outside, and sixteen external wires 52 become necessary to connect the anode terminals 3 and the cathode terminals 4 of the LED modules 50 to the control substrate 42, and in addition, the external wires running from the LED modules 50 provided at a distance from the control substrate 42 are long. Here, external wires are wires outside the LED modules, and referred to as external wires so as to be distinguishable from connecting wires, which are formed on the substrate within the LED modules.
In addition, FIG. 28 is a configuration diagram showing wires in the case where an LED light source apparatus where LEDs are aligned in a plane is formed by aligning the LED modules 51 in FIG. 26 in a 2×4 matrix. As compared to the LED module 50 in FIG. 25, the anode terminals 3 and the cathode terminals 4 are provided separately on facing sides, and therefore, though there are sixteen external wires 52 for connecting the anode terminals 3 and the cathode terminals 4 in the LED modules 50 to the control substrates 42, which is the same as for the LED modules 50, the external wires are longer.
Here, in the case where LEDs mounted in two LED modules 50 or 51 are connected in series, as shown in FIGS. 29 and 30, the number of external wires 52 for connecting the anode terminals 3 and the cathode terminals 4 of the LED modules 50 to the control substrate 42 can be reduced by half, but some of the external wires are still long.
As described above, in the case where a light source apparatus, such as a backlight, is formed by aligning a number of LEDs in a plane using a number of LED modules, wires for connecting the LED modules to a control substrate become necessary, irrespectively of the place where anode terminals and cathode terminals are provided. The smaller the LED modules are relative to the area illuminated by the light source apparatus, and the greater the number of LED modules used is, the longer the wires become, and the more problems there are with mounting the modules. Therefore, the greater the area to be illuminated is, the more LEDs can be mounted in the LED modules used. However, a problem arises, such that various types of LED modules must be prepared in accordance with the area to be illuminated by the light source apparatus.